This invention relates to therapeutic preparations in capsule or tablet form, and more particularly relates to such therapeutic preparations comprising particles having coatings thereover which are adapted to disintegrate at different times in the system of a patient thereby to provide for the timed release of a therapeutic material.
Timed disintegration capsules and tablets for the sequential, timed release of medicinal substances into a patient's system are well known in the art. Generally such capsules or tablets consist of particles containing the medicinal substance to be introduced into the system, and a coating over the particles of a material which is resistant to disintegration for a selected period of time. Such coating compositions are also referred to as enteric coating compositions, that is, compositions which are generally resistant to disintegration in the stomach, but which will disintegrate in the intestine. Enteric compositions also include compositions which are disintegratable so slowly in the stomach that the medicinal substance is not released until the capsule or tablet has reached the intestine of the patient. For example, coatings comprising bees wax and glyceryl monostearate; bees wax, shellac and cellulose; and cetyl alcohol, mastic and shellac have been proposed for use as slow release or timed release coatings for medicinal substances. Release of the medicinal substance by disintegration of the coating is generally controlled by controlling the thickness of the coating or by varying the coating composition.
The prior art compositions have generally proved deficient in that the medicinal substance is released so slowly in the system as to never reach the desired dosage level. Also, with many patients, the coatings are not disintegrated to the extent necessary to release the medicinal substance until the tablet or capsule has reached the colon and the medicinal substance is discharged from the system rather than absorbed by the intestine. Many prior art coating systems are not amenable to being formed into tablets or require the use of additive materials before the tableting operation, thereby raising the cost of manufacture.
The present invention, which also lies in the general area of timed disintegration coatings, represents a substantial improvement over the prior art compositions in that the time of disintegration is readily controllable and easily adjusted for release of a medicinal substance. In addition, the coating composition of the present invention may be utilized in tableting operations as well as in encapsulated therapeutic preparations.